Couplers are vehicle components used for coupling a locomotive with a carriage or a carriage with another carriage in order to transfer traction and impact force and keep a certain distance between carriages. FIG. 1 is a schematic diagram of an entire structure of a coupling system for train couplers; FIG. 2 is a schematic structure diagram of a mechanical coupler 6, where FIG. 2(a) is a schematic structure diagram of the mechanical coupler 6, FIG. 2(b) is a sectional view of the mechanical coupler 6 in a coupled state, and FIG. 2(c) is a sectional view of the mechanical coupler 6 in a to-be-coupled state after uncoupling; FIG. 3 is a state diagram of two mechanical couplers 6 when coupled; and, FIG. 4 is a schematic diagram of the airflow paths connection of a prior coupler uncoupling control mechanism. As shown in FIG. 1, a train coupler comprises a mechanical coupler 6 and two electrical couplers 5. The mechanical coupler 6 is connected to an uncoupling cylinder 4 used for uncoupling the mechanical coupler 6. Each of the electrical couplers 5 is connected to a propelling cylinder 3 capable of driving the electrical coupler 5 to do a reciprocating linear motion so as to realize coupling and uncoupling. Each of the electrical couplers 5 is slidingly connected to a guide rod 8 used for ensuring the linear motion of the electrical coupler 5. The guide rods 8 are mounted on guide mounting frames respectively on two sides of the mechanical coupler 6. Positioning pins 9 and positioning sleeves 10 are provided on the electrical couplers 5 to position the electrical couplers 5 during coupling.
As shown in FIG. 2, the mechanical coupler 6 mainly comprises a mechanical coupler body 61, a coupling rod 62 and a coupler knuckle 63. The coupling rod 62 is hinged to the coupler knuckle 63 and may be driven to do a reciprocating motion by the rotation of the coupler knuckle 63 in order to realize the coupling and uncoupling of two mechanical couplers 6. A spindle 64 is disposed in the center of the coupler knuckle 63 and the coupler knuckle 63 may drive the spindle 64 to synchronously rotate by a key 65. As shown in FIG. 2(a), the spindle 64 is fixedly connected to a cam 7, and the cam 7 is press-fitted with a first valve body 2 in a coupled state. In addition, as shown in FIG. 2(b), in the coupled state, the uncoupling cylinder 4 is disposed near the coupler knuckle 63; and, after stretched out, a cylinder rod of the uncoupling cylinder 4 may push the coupler knuckle 63 to rotate so as to realize the uncoupling of mechanical couplers 6.
As shown in FIG. 4, the airflow paths connection of a prior coupler uncoupling control mechanism is as follows: the uncoupling cylinder 4 is connected to an uncoupling pipe 12 (represented by an airflow path in this figure, where air enters from the end D) of the train by airflow path, each of the propelling cylinders 3 is connected to a main reservoir pipe 11 (represented by an airflow path in this figure, where main air is input to the main reservoir pipe 11 from the end C, and the main air is not only main air from an opposite coupled carriage but also main air supplied by this carriage) of the train by airflow path, and the first valve body 2 is connected between the propelling cylinder 3 and the main reservoir pipe 11.
As shown in FIG. 3, when two mechanical couplers 6 are to be coupled, the coupling rod 62 hooks the coupler knuckle 63 of the opposite mechanical coupler 6, realizing the coupling of two mechanical couplers 6. In this case, the state of each mechanical coupler 6 is shown in FIG. 2(b). When the two mechanical couplers 6 are to be uncoupled, the train issues a control signal for controlling the uncoupling pipe 12 to inflate air to the uncoupling cylinder 4 (that is, air enters from the end D), and the cylinder rod in the uncoupling cylinder 4 is stretched out and drives the coupler knuckle 63 to rotate clockwise. On one hand, as shown in FIG. 2(c), the clockwise rotation of the coupler knuckle 63 drives the coupling rod 62 to retract, so that the coupling rod 62 is uncoupled from the coupler knuckle 63 of the opposite mechanical coupler 6, realizing the uncoupling of the two mechanical couplers 6. On the other hand, the coupler knuckle 63 drives the spindle 64 to rotate by the key 65, so as to drive the cam 7 to rotate. When the cam 7 does not press the first valve body 2, the airflow path of the first valve body 2 is switched, and the flow direction of airflow in the propelling cylinder 3 is changed. As a result, the cylinder rod of the propelling cylinder 3 is changed from a stretched state to a retracted state, and the electrical couplers 5 are retracted along the guide rods 8, until the electrical couplers 5 of the train are uncoupled.
However, since the uncoupling process of the mechanical coupler 6 is prior to that of the electrical couplers 5 (the electrical couplers 5 begins to be uncoupled only when the airflow path in the first valve body 2 is switched), it is very likely that the uncoupling processes of the electrical couplers 5 have not completed when the uncoupling process of the mechanical coupler 6 is completed. In this case, the positioning pins 9 on two coupled electrical couplers 5 are not separated from the positioning sleeves 11 on the opposite electrical couplers 5. Since the mechanical coupler 6 has been uncoupled at this time, the couplers of two coupled carriages that are not completely uncoupled will form an angle under gravity due to the difference in height (the height of the couplers may be different due to an air spring or the like). As a result, the guide rods 8 mounted on the guide mounting frames on two sides of the mechanical coupler 6 will force the coupled electrical couplers 5 of two trains have a tendency to form a certain angle, thereby generating a large local contact force between the connected positioning pins 9 and positioning sleeves 10. This local contact force will affect the uncoupling operation of the electrical couplers 5 or even cannot complete the uncoupling of the electrical couplers 5 due to seizure.